A 16-year-old boy is brought to the emergency department by his mother after a single episode of generalized tonic-clonic seizure. The patient has been staying up late studying for midterm exams and has been feeling "more tired than usual" for the last few days. For the last 6 months, he has had occasional jerking arm movements in the morning but was not medically evaluated as they were brief and he otherwise "felt fine." The patient has had no recent fevers, vomiting, or headaches. He does not use alcohol or illicit drugs. His mother describes him as "anxious," but he has no chronic medical conditions and takes no medications. Temperature is 37.2 C (99 F), blood pressure is 120/60 mm Hg, and pulse is 72/min. On physical examination, the patient is drowsy but responsive to commands and oriented to person, place, and time. Cardiac examination reveals a regular rate and rhythm without murmurs. Cranial nerves II-XII are intact; there are no focal deficits. Deep tendon reflexes are normal in the upper and lower extremities, and plantar responses are flexor. There are no rashes or petechiae. Electroencephalogram shows bilateral polyspike and slow wave discharges. The patient receives appropriate treatment. He will require long-term monitoring for which of the following medication side effects?

Question

A 16-year-old boy is brought to the emergency department by his mother after a single episode of generalized tonic-clonic seizure.  The patient has been staying up late studying for midterm exams and has been feeling "more tired than usual" for the last few days.  For the last 6 months, he has had occasional jerking arm movements in the morning but was not medically evaluated as they were brief and he otherwise "felt fine."  The patient has had no recent fevers, vomiting, or headaches.  He does not use alcohol or illicit drugs.  His mother describes him as "anxious," but he has no chronic medical conditions and takes no medications.  Temperature is 37.2 C (99 F), blood pressure is 120/60 mm Hg, and pulse is 72/min.  On physical examination, the patient is drowsy but responsive to commands and oriented to person, place, and time.  Cardiac examination reveals a regular rate and rhythm without murmurs.  Cranial nerves II-XII are intact; there are no focal deficits.  Deep tendon reflexes are normal in the upper and lower extremities, and plantar responses are flexor.  There are no rashes or petechiae.  Electroencephalogram shows bilateral polyspike and slow wave discharges. The patient receives appropriate treatment.  He will require long-term monitoring for which of the following medication side effects?

Quizplus · Accepted Answer

Explanation: Patients with juvenile myoclonic epilepsy are at risk for recurrent seizures and require lifelong antiepileptic drugs (AEDs). A baseline AED level is typically obtained and the dose gradually titrated until seizures are suppressed or the patient is at risk for toxicity. Valproic acid (VPA) is a broad-spectrum anti-seizure medication that can cause dose-related thrombocytopenia and potentially suppress other cell lines. At treatment initiation, a complete blood count with platelets should be obtained and then followed periodically. VPA can cause life-threatening hepatotoxicity and pancreatitis; liver enzymes should be measured intermittently, and lipase should be obtained in any patient with acute abdominal pain. VPA is also a known teratogen that has been linked to neural tube defects; it should be used with caution in women of child-bearing age. (Choice A) Initiation of tricyclic antidepressants requires a baseline ECG and monitoring due to risk of arrhythmia. However, cardiotoxicity is not a common side effect of AEDs. (Choice B) Gingival hyperplasia is an important side effect of the AED phenytoin but is not associated with VPA. (Choice C) Hyponatremia due to inappropriate antidiuretic hormone release is a side effect of the AED oxcarbazepine but not of VPA. (Choice D) Tardive dyskinesia can occur with antipsychotic medications due to prolonged blockade of dopamine receptors, but it does not occur with VPA. Educational objective: Valproic acid is a broad-spectrum anti-seizure medication that can cause thrombocytopenia and hepatotoxicity; patients taking this medication should be monitored for these side effects. Valproic acid is also a known teratogen that has been linked to neural tube defects. References: Management of juvenile myoclonic epilepsy. (http://www.ncbi.nlm.nih.gov/pubmed/23756489)

A 16-Year-Old Boy Is Brought to the Emergency Department by His